The present invention relates to an electrophotographic apparatus having imaging means utilizing an electrophotographic process.
Conventionally, an electrophotographic apparatus, having imaging means utilizing an electrophotographic process, is provided with a photoconductive drum, a developing device for developing a latent image formed on the outer peripheral surface of the photoconductive drum by a toner, and a transfer charger for transferring the developed image onto a sheet. The transfer charger of the conventional electrophotographic apparatus, in which one side surface of an enclosure of the apparatus is set to be openable over the total area of the one side surface, is capable of being inserted into or out of the enclosure In which the photoconductive drum is rotatably supported. More specifically, the transfer charger is set to be movable in the enclosure in a direction parallel to the rotary axis of the photoconductive drum.
In the conventional electrophotographic apparatus, when the sheet is jammed between the photoconductive drum and the transfer charger in the enclosure, the transfer charger must be pulled out from the enclosure in order to release the jammed sheet. In this case, it is possible that the jammed sheet is broken because the transfer charger which is being pulled out from the enclosure, engages the jammed sheet. Thus, the broken piece of the jammed sheet remains in the enclosure.
Alternative, electrophotographic apparatus has been developed wherein the upper surface of the enclosure is set to be openable. In the conventional structure of the upper surface openable type, the transfer charger is arranged in the enclosure in a fixed manner. Accordingly, when the sheet is jammed between the photoconductive drum and the transfer charger, the upper cover, for covering the upper opening of the enclosure, must be opened. Once the upper cover is opened, the outer light is allowed to enter into the enclosure through the opened upper opening. As a result, the outer peripheral surface of the photoconductive drum is exposed to the light entering through the opened upper opening. The photoconductive layer formed on the outer peripheral surface of the photoconductive drum causes an optical fatigue phenomenon, thereby lowering the characteristic of the photoconductive property in the photoconductive layer.
Furthermore, in the conventional electrophotographic apparatus, the sheet is fed along a feeding path which includes at least a transfer position defined between the photoconductive drum and the transfer charger. In the feeding path, when the sheet passes through the transfer position, there is no provision for urging the trailing end or the upstream side end of the sheet onto the outer peripheral surface of the photoconductive drum so as to contact thereto. Accordingly, the trailing end of the sheet is remote from the outer peripheral surface of the photoconductive drum when the sheet passes through the transfer position. As a result, that portion of the toner image on the outer peripheral surface of the photoconductive drum, which is to be transferred to the trailing end of the sheet, has not been transferred even though the trailing end of the sheet actually passes through the transfer position.